More than 100 vehicles were involved in a massive motorway pile-up today which left two people dead.

Several people were seriously hurt in about 20 "knock-on" accidents between junctions five and eight on the southbound carriageway of the M40 in Oxfordshire at Lewknor, Thames Valley Police said.

In thick early morning fog, fire crews had to cut people free from the wreckage at the scene between High Wycombe and Oxford where a motorcyclist, a man who has not been named, was killed in a crash with a van. A second man died later in hospital.

Two people were in a "critical" condition in Oxford's John Radcliffe Hospital and at least 18 were receiving treatment there and in the Wycombe General hospital in High Wycombe.

The pile-up, which happened at about 7am, has caused a six mile-long tail-back in the immediate area, with the M40 southbound still closed between junctions five and eight.

Police said disruption was likely to last for several hours and more road chaos was predicted after the M5 in Somerset had to be closed in both directions when a lorry was in collision with a car.

Debris was mostly cleared by late afternoon and the road was expected to re-open in the early evening.

Motoring organisations said the huge pile-up came at a particularly busy time, with families driving away for the Easter holiday.

Rebecca Rees, from the AA, said for people stuck in the traffic queues behind the accident, it was "a horrendous situation".

"Maundy Thursday is always a difficult day traffic-wise as it is the start of the Easter rush. This accident will just make things worse," she said.

The RAC said the accident was "particularly tragic", coming at Easter when there were many more vehicles on the roads as families took their cars on holiday.

Both organisations warned motorists to take extra care when driving in fog.

Meanwhile, in the West Country police were forced to close one of the country's busiest motorways following the lorry smash.

The crash happened on the northbound carriageway of the M5 in Somerset near Sedgemoor Services, when an articulated lorry collided with a car and careered into a field.

Police said the lorry's trailer had tipped over, completely blocking the carriageway.

The motorway was closed in both directions between junction 22 at the turning for Burnham-on-Sea, and junction 21, at Weston-super-Mare.

It is not yet known whether anybody was killed or injured in the crash, which happened just before 10am.

Motorists were advised to avoid both areas unless "absolutely necessary".

Thames Valley Police have set up an emergency helpline for people concerned that their friends and relatives could be involved in the Lewknor pile-up. The number is: 08459 441 551.